1. Field of the Invention
The present invention relates to a non-interrupted operation control apparatus for a modulator-demodulator, and more specifically it relates to non-interrupted operation control for the purpose of operating a modulator-demodulator for a long period of time.
In data-processing equipment (hereinafter referred to as controllers) such as computer terminals which operate or are in the standby condition for a number of days continuously, and use a modulator-demodulator (hereinafter referred to as modem), externally introduced noise or radiation and the like can cause corruption of the parameter data held in the internal non-volatile memory of the modem, causing the modem to fail to operate or causing the modem circuit to hang up and thereby stop operating. For this reason, there is a need for a non-interrupted operation control apparatus for a modem which prevents the abnormal communications conditions which cause such phenomena.
2. Description of the Related Art
In a modem operation control apparatus having a control section, a modem section and a power supply, the modem section is modularized and made to be generally usable by allowing control parameters to select the communications mode and the like. Fixed parameters are first set into non-volatile memory, and hardware-specific parameters such as communications speed and test method are set into internal registers in the modem from the control section when the main power switch is used to apply power.
When the power is applied, the reset section of the modem section performs an internal reset of the modem. In the control section, an initialization section performs a hardware reset and initialization within the control section, after which the parameter setting section is started, whereby parameter setting commands are issued to the modem section. In the modem section, when a command interpreting section recognizes these commands, parameters from the above-noted controller are set into the above-noted registers.
However, modems are often left powered up or in the standby condition for many days. For this reason, externally introduced noise or radiation can cause corruption of the settings of control parameters which are set in non-volatile memory, this resulting in endless software loops or halt conditions and this hanging the circuit or resulting in abnormal communications conditions.
In the waiting-for-call condition, from the standpoint of reduction of cost and an increase in the life of the equipment, one can envision turning off the supply of power to the control section. However, in this type of equipment, this would lead to the problem of not being able to monitor modem problems such as described above.